VOLUME 1
`Pages 1- 1090
`(January-April)
`
`1970
`
`METALLURGICAL
`TRANSACTIONS
`
`Published Jointly by
`The American Society for Metals
`and
`The Metallurgical Society of AIME
`
`Copyright 1970
`
`COOK
`Exhibit 1010-0001
`
`

`

`Engln Ul>ri"\7
`
`SPECIAL LECTURES
`
`The 1970 Extractive Metallurgy Lecture
`The Metallurgical Society of AIME
`Industrial Research in Extractive Metallurgy
`
`Carleton C. Long ..... . .. . .... .. 753
`
`The Forty-seventh Henry Marion Howe Memorial Lecture
`The Metallurgical Society of AIME
`Henry Marion Howe
`
`James B. Austin .. .. .. .. . ..... .. 1795
`
`The 1970 Institute of Metals Lecture
`The Metallurgical Society of AIME
`Superconductivity and Physical Metallurgy
`
`The 1970 Campbell Memorial Lecture
`The American Society for Metals
`
`Alfred Seeger . . ... .... . .. . ..... 2987
`
`Perspectives on Corrosion of Materials
`
`Mars G. Fontana . .. .... .... .... 3251
`
`METALLURGICAL CLASSICS
`
`The Influence of Heat on the Molecular
`Structure of Zinc
`Commentary by Karl T. Aust
`
`Transformation of Austenite at Constant
`Subcritical Temperatures
`Commentary by Harold W. Paxton
`
`Salomon Kalischer .... .. . . .. ... . 2066
`.. . .... . ... .. . . . ... ... . .. .. .. 2055
`E. S. Davenport and
`E. C. Bain .......... ... .... . . .. 3502
`. . .... . . .. .. .. .... . . . . .... . .. 3479
`
`Paul C
`
`Paul
`
`Car!E
`
`H. l
`T. I
`G . .
`c. :
`R. '
`R.
`J. I
`N.
`J. J
`J. C
`D.
`R.
`T.
`J.:
`y.
`G.
`
`Plll
`tut
`47
`AI
`(2
`sti
`tic
`
`COOK
`Exhibit 1010-0002
`
`

`

`METALLURGICAL
`TRANSACTIONS
`
`VOLUME I,NUMBER I
`
`JANUARY 1970
`
`Published jointly by
`The Metallurgical Society of AIME, 345 East 47th Street, New York, N. Y. 10017
`American Society for Metals, Metals Park, Ohio 44073
`
`Paul G. Shewmon, Chairman
`
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`OFFICERS
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`Review and selection of manuscripts are under the supervision of the
`Board of Review consisting of appointed members from TMS and ASM.
`
`H. I. Aaronson
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`R. W. Bartlett
`J. F. Breedis
`N. N. Breyer
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`J. F. Enrietto
`D. J . I. Evans
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`D.R. George
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`K. Gschneidner, Jr.
`D. J. Hansen
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`R. W. Heckel
`T.A. Henrie
`M. T. Hepworth
`J. E. Hilliard
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`J. J. Hren
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`J . J.Jonas
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`T. F. Kassner
`
`L. Kaufman
`R. W. Kraft
`A.H. Larson
`A. Lawley
`H. J. Levinstein
`C. Y. Li
`J.C. M. Li
`H. A. Lipsitt
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`F.S.Manning
`J. R. Manning
`F. D. McCuaig
`A. J. McEvily
`R. B. Mclellan
`C. J. McMahon, Jr.
`J. T. Michalak
`
`Y. Nakada
`M. V. Nevitt
`R. G. Olsson
`H. R. Peiffer
`F. S. Pettit
`D. R. Poirier
`H. Pops
`L. F. Porter
`G. M. Pound
`S. Ramachandran
`A. R. Rosenfield
`A. W. Ruff, Jr.
`K. C. Russell
`H. W. Schadler
`G. Simkovich
`E. A. Steigerwald
`
`D. F. Stein
`C. P. Sullivan
`S. K. Tarby
`J.M. Toguri
`E. E. Underwood
`C. M. Wayman
`J. Weertman
`A. F. Weinberg
`M. S. Wechsler
`F. V. Williams
`P. G. Winchell
`M.M. Wong
`W. L. Worrell
`W. V. Y oudelis
`A. 0. Zunkel
`
`Published monthly by The Metallurgical Society of American Insti(cid:173)
`tute of Mining, Metallurgical, and Petroleum Engineers, Inc., 345 East
`47th Street, New York, N.Y. 10017, Telephone (2 12) 752·6800, and
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`ety for Metals ... Indexed by major abstracting services... Application
`to mail at 2nd class postal rates is pending at Novelty, Ohio, and additional
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`
`COOK
`Exhibit 1010-0003
`
`

`

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`
`METALLURGICAL
`TRANSACTIONS
`
`PUBLISHED JOINTLY BY THE METALLURGICAL SOCIETY OF AIME AND AMERICAN SOCIETY FOR METALS
`
`To the Readers of METALLURGICAL TRANSACTIONS:
`
`This first issue of METALLURGICAL TRANSACTIONS marks a major advance in
`the metallurgical profession. Two eminent publications, the TRANSACTIONS
`of The Metallurgical Society of AIME and the TRANSACTIONS QUARTERLY of
`the American Society for Metals, have now been merged into a single out(cid:173)
`standing journal. Thus, our two sponsoring Societies are henceforth
`joined in the publication of high-standard papers dealing with a broad
`spectrum of metallurgically-oriented research and development. The
`Boards of TMS and ASM are confident that this new medium of information(cid:173)
`dissemination in the field of metals science and engineering will serve
`its readers more effectively and comprehensively, as well as more
`economically, than would otherwise be possible.
`
`In behalf of the metallurgical generations yet to come, and as Presidents
`of the respective Societies, we extend our collective appreciation to the
`connnittees and staff-members of both organizations whose vision and
`devoted efforts brought this new journal into existence.
`
`orr s Cohen, President
`Ame ·:-can Society for Metals
`Metals Park, Ohio
`
`Paul Queneau, President
`The Metallurgical Society of AIME
`New York, New York
`
`ADDRESS REPLY TO: THE METALLURGICAL SOCIETY, 345 EAST 47 STREET. NEW YORK. N.Y. 10017
`
`COOK
`Exhibit 1010-0004
`
`

`

`Stress-Induced Pseudoelasticity in Ternary Cu-Zn Based
`Beta Prime Phase Alloys
`
`HORACE POPS
`
`"Pseudo"elastic strains up to approximately 15 pct have been observed in ternary Cu- Zn-Si
`and Cu-Zn-Sn {31 phase alloys during loading in tension, compression, or bending. Metallo(cid:173)
`graphic observations and mechanical property studies have shown that the unusually large
`elastic strains occur by means of a stress- induced martensitic transformation. The relation(cid:173)
`ship between spontaneous martensite and stress-induced martensite is discussed. The influ(cid:173)
`ence of temperature, composition, plastic flow stress, and elastic modulus upon the transfor(cid:173)
`mation induced pseudoelasticity are discussed.
`
`IT is characteristic of the bee /3 ' phases that they
`transform martensitically during cooling and that this
`transformation is very sensitive to strain . In a few
`systems, s uch as Cu-Zn, 1 the martensite phase may
`form "thermoelastically", during which process the
`martensite plates grow as the temperature is lowered
`and shrink upon heating, with little or no temperature
`hysteresis. It is also common for a similar form of
`martensite to gr ow during application of stress and to
`shrink or disappear when the load is removed. The
`formation under stress of a reversible "elastic"
`martensite may result in rubber-like properties .
`This has been reported for In-Tl,2 Au-Cd,3 and Cu-Al(cid:173)
`Ni4 alloys. The term "super-elasticity" was used
`by Rachinger4 in 1960 to describe the large elastic
`strains (-4 pct) which occurred at room temperatur e
`during the stressing of single crystals of Cu-14. 5
`Al-3 Ni alloys. Superelastic behavior has also been
`observed in coarse grained polycrystalline Cu-Al-Ni
`alloys . 5 Much attention has been focussed recently
`on the NiTi alloys 6 (the Nitinols) which show a very
`unusual mechanical "shape-memory" effect as a re(cid:173)
`sult of a martensitic transformation.
`Thermoelastic martensite was studied in previous
`investigations7
`>8 of ternary alloys based upon the
`Cu-Zn {3 ' brass phase (Cu-Zn-Ni, Cu-Zn-Ag, Cu-Zn(cid:173)
`Au, Cu-Zn-Cd, Cu-Zn-In, Cu-Zn-Ga, Cu-Zn-Si,
`Cu-Zn-Ge, Cu-Zn-Sn, and Cu-Zn- Sb). The data indi(cid:173)
`cated that by a suitable choice of composition, these
`alloys might show rubber-like behavior under stress
`near room temperature. On the basis of preliminary
`experiments ,9 the systems Cu-Zn- Si and Cu-Zn-Sn
`were selected for further detailed studies. The object
`of this research was to determine the extent of elas(cid:173)
`ticity occurring as a result of the elastic martensite
`transformation. The role of applied stress, transfor(cid:173)
`mation temperature, and test temperature was also
`examined.
`
`!)EXPERIMENTAL PROCEDURE
`
`Alloys were chosen on the basis of their transfor(cid:173)
`mation temperatures, see Fig. 1, which depend upon
`chemical composition. M5 temperatures were se-
`HORACE POPS is Senior Fellow, Mellon Institute, Carnegie-Mellon
`University, Pittsburgh, Pa.
`Manuscript submitted May 27, 1969.
`
`lected in the range between room temperature and
`approximately -50°C. Six Cu-Zn-Si and Cu-Zn-Sn
`alloys, each corresponding to an electron-to-atom
`ratio of 1.395, were prepared and their nominal com(cid:173)
`positions are given in Table I. High-purity metals
`(>99.99 pct) were used, the alloys being melted and
`cast in sealed quartz tubes under a partial pressure
`of helium . Samples were homogenized in evacuated
`quartz capsules held for 24 hr at temperatures within
`the single {3-phase field,1 ° -790° to 830°C. Since weight
`
`Table I. Compositions of Alloys in at. pct, Used for Deformation Studies
`
`Alloy
`
`A
`B
`C
`D
`E
`F
`
`Cu
`
`62.5
`63.3
`64 .1
`62.9
`63.8
`64.9
`
`Zn
`
`36.5
`35.3
`34.1
`35.9
`34.55
`31.9
`
`Si
`
`1.0
`1.4
`1.8
`
`Sn
`
`1.2
`1.65
`2 .2
`
`Sn
`
`0
`
`- 50
`
`or
`~ - 100
`0 ...
`
`Q>
`Q.
`
`~ - 150 ·
`f-
`"' ~
`-200
`
`-250
`
`0
`
`2
`1
`Atomic % So l ute
`Fig. I-Transformation temperature (Ms) of ternary alloys
`based upon the Cu- Zn {3 1 phase. el a = 1.395.
`
`3
`
`MET ALLURGICAL T RANSA CTIONS
`
`VO L UME ) ,JANUARY 1970- 2 51
`
`COOK
`Exhibit 1010-0005
`
`

`

`losses were negligible, the compositions after melting
`and homogenization were assumed to be the same as
`the nominal compositions. In order to prevent pre(cid:173)
`cipitation of the fee a phase, the alloys were quenched
`from the homogenizing temperature into an iced brine
`solution. Metallographic examination was carried out
`on samples electropolished in a 10 pct solution of KCN
`in water using alternating current. The samples were
`completely (3' prior to the mechanical deformation
`studies and exhibited a coarse grain size (- 1 to 5 mm).
`An Instron machine was used for tensile tests, three(cid:173)
`point bending, and compressive loading. Testing was
`done at temperatures between the Ms of the sample
`and approximately l00°C. A liquid (in most cases
`water) was used to maintain a constant specimen tem(cid:173)
`perature for the tension and compression tests. The
`progress of the transformation occurring during load(cid:173)
`ing of a bend sample was observed using a Reichert
`Metallograph and a specially constructed deformation
`jig. Several single crystals were grown by the Bridg(cid:173)
`man technique and were used for compression studies.
`
`II)RESULTS
`
`A) Effect of Applied Uniaxial Stress. The tensile
`curve of a typical Cu- Zn based ternary alloy is shown
`in Fig. 2. Upon initial loading, stress increases
`linearly with strain. With further loading, the stress(cid:173)
`strain relationship is very much different from that of
`conventional polycrystalline materials. When the load
`is increased beyond what appears to be the proportional
`limit, the curve becomes nearly horizontal and the
`strain increases approximately 10 pct in this plateau
`region. At higher loads, the stress again varies lin(cid:173)
`early with strain, and the point of deviation from
`linearity has been termed the plastic yield point. The
`total strain measured up to this point appears to indi(cid:173)
`cate a seemingly elastic nature because the specimen
`acquires little or no permanent deformation (set) after
`unloading. Apparent elastic strains as high as 15 pct
`have been measured in coarse grain polycrystalline
`specimens. In several specimens of alloy F a reduction
`in the cross section was detected visually at high
`strains, but disappeared when the load was removed.
`Serrations were generally visible in the plateau re-
`
`I
`
`I
`,?
`
`Plastic
`Y.P.
`
`20
`
`15
`
`5
`
`5%
`
`10%
`Percentage Strain
`Fig. 2-Typical stress- strain curve for a silicon- bearing
`alloy deformed in tension at room temperature. Total elas(cid:173)
`tic strain is -15 pct.
`
`15 %
`
`gion of the tensile curve, as may be seen in Fig. 3.
`· Upon unloading, the stress drops rapidly at first, and
`then becomes nearly horizontal, producing a charac(cid:173)
`teristic hysteresis loop. As in the case of loading,
`serrations are visible in the horizontal portion of the
`unloading curve. The shape of the curve in this re(cid:173)
`gion was quite irregular and differed from sample to
`sample. Although a small permanent set usually re(cid:173)
`mained in the test sample after unloading, large elas(cid:173)
`tic strains were r eproduced upon reloading.
`The point of deviation from linearity in the tensile
`curves prior to the plateau region occurred at differ(cid:173)
`ent values of stress depending upon the alloy composi(cid:173)
`tion. Assuming that a strain induced martensitic trans(cid:173)
`formation occurs at the point of deviation, the stress
`required to induce this transformation ought to be
`dependent upon the strength or stability of the ma-
`trix and, therefore, the temperature at which the sam(cid:173)
`ple is deformed. Accordingly, polycrystalline tensile
`specimens of several ternary Cu-Zn-Si and Cu-Zn-Sn
`alloys were deformed elastically over the temperature
`range between the Ms of the alloy and 100°c. Fig. 4(a)
`shows the stress-strain curves at temperatures be(cid:173)
`tween 27° and 78°C for a silicon-bearing alloy. The
`stress at departure from linearity on loading is plotted
`as a function of test temperature in Fig. 4(b). At the
`lower test temperatures, very little stress is required
`to induce the transformation. As the test temperature
`is increased, stress also increases. The plot of load(cid:173)
`ing-stress vs temperature results in a straight line
`which extrapolates to the M 5 temperature at zero
`stress . Data obtained from the unloading curves also
`give a straight line plot, but in this case extrapolate
`
`12
`
`8
`
`·-VI a.
`
`It)
`I
`0
`
`X
`VI
`VI
`Q)
`
`... 4
`
`CJ)
`
`2
`
`5
`4
`3
`2
`Percentage Strain
`Fig. 3-Portion of tensile curve for a ternary Cu- Zn-Sn al(cid:173)
`loy deformed at r oom temperature showing characteristic
`hysteresis loop after unloading. Serrations are associated
`with the formation of elas tic ma rtensite.
`
`6
`
`7
`
`252-VOLUME I , JANUARY 1970
`
`METALLURGICAL TRANSACTIONS
`
`COOK
`Exhibit 1010-0006
`
`

`

`to the initial transformation temperature during heat(cid:173)
`ing (As) at zer o stress. Similar behavior was ob(cid:173)
`served for all ternary alloys containing silicon; the
`tensile stress required to initiate a martensitic trans(cid:173)
`formati on became zero at the Ms temperature.
`Tensile stress-strain curves for the Cu-Zn-Sn
`alloys were similar t o those described for the Cu-Zn(cid:173)
`Si alloys, as shown in Fig. 5(a). The stress upon load(cid:173)
`ing becomes zero near the Ms temperature and in(cid:173)
`crease s linearly with increasing test temperature.
`Some of the tensile curves contain two peak maxima,
`each resembling a plastic yield point (see curve for
`57°C); however , little or no permanent set was ob(cid:173)
`served after unloading. Since the samples had very
`large grains, it is assumed that these elastic insta(cid:173)
`bility points are associated with the onset of a mar(cid:173)
`tensitic transformation in different grains. It should
`be noted that the applied tensile stress produces
`
`plastic deformation at 81°C, but no permanent set
`occurs in samples tested below 78°C. Therefore, for
`this particular specimen , pseudoelasticity occurs in
`the temperature range between - 6°C (the Ms) and less
`than 8l°C.
`Large elastic strains were also produced in the ter(cid:173)
`nar y beta brass type alloys by compressive loading.
`A representative stress-strain curve for a single crys(cid:173)
`tal of Cu-Zn-Si is shown in Fig. 6. This cur ve indi(cid:173)
`cates typical features of transformation induced
`pseudoelasticity in that it exhibits an initial region
`during which stress is proportional to strain, a
`plateau region where the "apparent" elastic modulus *
`
`•The slope of the stress-strain curve does not give the true elastic modulus of
`the matrix, but indicates the occurrence of a phase transformation. The strains are
`not elastic in a t rue sense, rather the martensitic process results in "pseudo" elastic
`strains which resemble elasticity in that the strain is reversible.
`
`1a•c
`
`decreases to zero or becomes negative, a hysteresis
`loop, and large elastic strains. The procedure of load(cid:173)
`ing and unloading a polycrystalline compression sam(cid:173)
`ple at one temperature and repeating the cycle at dif(cid:173)
`fer ent test temperatures produced transformation
`stress vs test temperature results shown in Fig. 7.
`
`20
`
`18
`
`16
`
`14
`
`"[12
`'?
`~10
`X
`~ 8
`V>
`6
`
`V,
`V,
`
`4
`
`2
`
`0
`
`20
`
`18
`
`16
`
`14
`
`! 12
`"' I
`0
`-10
`X
`"' "' ~ 8
`in
`
`6
`
`4
`
`2
`
`Percentage Strain
`(a)
`
`D .. ·r •
`
`/
`
`(T
`
`o Load
`D Unload
`
`(a)
`
`0
`
`0
`
`<T
`
`0Ld DL
`
`•
`
`o Load
`o Unload
`
`20
`
`18
`
`16
`
`14
`
`112
`'?
`0
`- 10
`X
`"' "' ~ 8
`in
`
`6
`
`4
`
`2
`
`o,.__ _ _.__ '1--_ _J_ _ __. __ ,__...L-_ ....._ _ _._ _ __. _ _ ,__
`· 20
`· 10
`10
`20
`30
`40
`50
`60
`70 80
`Test Temperature, •c
`Ms
`(b}
`Fig. 5-Variation of pseudoelasticity with test temperature
`for Cu-Zn-Sn alloy F deformed in tension. (a) Stress-strain
`curves showing onset of transformation and plastic deforma(cid:173)
`tion. (b) Stress vs temperature for loading and unloading.
`
`-9o
`
`Ms As
`
`30 40 50 60 70 80 90
`Test Tempera ture, •c
`(b)
`Fig. 4-Effect of temperature upon the tensile behavior of
`Cu- Zn- Si alloy C. (a) Stress - strain curves at different test
`temperatures. (b) Variation of stress required to produce
`martensitic transformation with test temperature.
`
`META LLUR GICAL TRANSACTIONS
`
`VOLUME J, JAN UARY 1970- 253
`
`COOK
`Exhibit 1010-0007
`
`

`

`32
`
`28
`
`<I)
`a.
`..,
`I
`0
`
`X
`<I)
`<I)
`<I)
`
`,_
`(/) 12
`
`8
`
`4
`
`2
`
`6
`4
`8
`Percentage Strain
`Fig. 6-Stress- stra in curve at 27°C for a single crystal of
`Cu-Zn-Si alloy C deformed in compression.
`
`10
`
`12
`
`C,
`/
`0
`0~
`
`16
`
`14
`
`12
`
`10
`
`in
`Q.
`
`"' I
`0
`X
`
`V)
`<I'>
`~
`(f)
`
`8
`
`6
`
`Test Temperature, (°C)
`
`Fig. 7-T r ansformation stress vs temperature for alloy C
`deformed by compressive loading.
`
`As in the case of tensile loading, the stress corre(cid:173)
`sponding to the departure from linearity in the stress(cid:173)
`strain curve increased linearly with increasing test
`temperature. Similar trends were also observed when
`the stress obtained from the unloading curve was
`plotted against the test temperature.
`B) Martensitic Transformation Under Bending
`Stress. A typical load vs deflection curve for a Cu(cid:173)
`Zn-Si sample deformed at room temperature is shown
`in Fig. 8. On bending the specimen, large deflections
`are produced and the apparent elastic modulus ap(cid:173)
`proaches zero. Upon unloading, the specimen snaps
`back to its original shape, characteristic of "rubber(cid:173)
`like" behavior. A hysteresis loop was observed in all
`specimens exhibiting this type of behavior. Metallo(cid:173)
`graphic examination during loading revealed that
`plates (traces are formed in the plane of polish by a
`section through the martensite. The traces will be
`referred hereafter as plates, or platelets.) of a mar(cid:173)
`tensitic phase form and grow side-by-side into the (3'
`phase matrix under the application of stress. Fig. 9
`shows a plot of length of plate vs deflection for a
`Cu-Zn-Sn sample deformed elastically at room tem(cid:173)
`perature. A small increase in deflection (proportional
`to the applied strain) produces a small increase in
`
`Pj
`
`Z:-::.::::¥:::>A ::;=o.oa, ..
`
`1-- 1.7"- - J
`
`10
`
`.02
`
`03
`
`.04
`
`.a, 06
`10
`.09
`.OB
`.0 7
`0£FLECTIO N, $, fnches.
`Fig. 8-Typical load vs deflection curve for pseudoelastic
`alloys deformed in three point bending, alloy B.
`
`.I I
`
`.12
`
`.13
`
`.14
`
`,,
`
`16
`
`Needle No.
`
`Deflection
`
`0 2 ~
`• 1
`
`0 3
`8 4
`
`0
`
`4
`
`·= 3
`..,
`0
`
`X
`<l)
`
`0
`
`02
`a. ....
`..c -0, a; 1
`
`_J
`
`0
`
`0.01
`
`0.02
`0.03
`Deflection (in)
`Fig. 9-Growtb of elastic martensite with bending stress in
`alloy A.
`
`0.04
`
`0.05
`
`254- VOLUME l , JA NUAR Y 1970
`
`METALLURGICAL TRANSACTIONS
`
`COOK
`Exhibit 1010-0008
`
`

`

`length. The arrest in growth occurred when marten (cid:173)
`site impinged upon grain bounda1ies of the /3' phase.
`The first platelets that were observed to grow
`were those already present, and most likely were
`produced by initial mechanical polishing. A number
`of new plates subsequently nucleated at the compres(cid:173)
`sion side of the sample and grew into the matrix with
`increasing stress. Their appearance corresponded to
`a point of departure from linearity in the load vs de(cid:173)
`flection curve. Transformation generally occurred at
`the compressive side with individual grains respond(cid:173)
`ing differently to the applied stress. This suggests
`that the formation of elastic martensite is dependent
`on the orientation of the grains. Marten site plates
`stopped growing at a precipitates or at the original
`/3' phase grain boundaries, as shown in Fig. 10. They
`decreased in length upon unloading and usually disap(cid:173)
`peared when the load was removed. The plates which
`formed last upon loading disappeared first upon un(cid:173)
`loading but were stable to a lower stress level on
`unloading.
`When the sample was reloaded, martensite formed
`at identical locations in the structure. A simple bend(cid:173)
`ing experiment was conducted to show the effects of
`stress (tensile vs compressive) upon the transforma(cid:173)
`tion behavior, see Fig. 11. The photomicrographs
`shown in Fig. ll(a) was obtained from the tensile side
`of a bend sample. Several different variants of the
`martensite habit plane are visible in each grain. Most
`of the plates disappeared when the load was removed,
`Fig . ll(b). When the area shown in Fig. ll(a) was re(cid:173)
`loaded under compressive stress, the strain induced
`martensite formed on different habit planes, see Fig.
`
`, .
`
`•
`
`,/
`
`.... ..
`
`.i.
`
`(a)
`
`/
`
`/
`
`/
`
`(b)
`
`(c}
`
`Fig. 10-Martensite plates formed by elastic deformation in
`alloy A. Magnification 80 times.
`
`Fig. 11-Martensite formation under elastic bending stress
`in alloy F. (a) Tension side of the sample. (b) Load removed.
`Note lack of martensite plates. (c} Reloaded in compression.
`Note martensite plates lying on different planes from those
`shown in (a).
`
`METALLURGICAL TRANSACTIONS
`
`VOLUME I , JANUARY 1970-255
`
`COOK
`Exhibit 1010-0009
`
`

`

`11 (c ). While loaded elastically , the specimen was
`cooled below the Ms until spontaneous martensite
`formed . It was observed that many of the existing
`strain-induced martensite plates decreased in length
`and disappeared, while other plates grew in length.
`Also, some of the thermoelastic martensite phase
`formed along different planes (possibly different var(cid:173)
`iants of the same plane) in the matrix.
`Elastic martensite very often has a different mor(cid:173)
`phology from martensite formed by plastic deforma(cid:173)
`tion. Fig. 12(a) shows a region near the fracture sur(cid:173)
`face of a permanently deformed tensile sample. The
`
`(a)
`
`(b)
`
`Fig. 12-Martensite formation in alloy E deformed plastically
`in tension. (a) Martensite formation resulting from heavy
`deformation. Magnification 77 times. (b) Interaction between
`martensite platelets. Higher magnification.
`
`strain-induced martensitic phase is wavy when defor(cid:173)
`mation is relatively heavy and broader than the elastic
`martensite. Intersection between different platelets is
`common, and often results in a microstructure simi(cid:173)
`lar to that shown in Fig. 12(b); this has a more regular
`pattern, and is similar to the thermoelastic martensite.
`C) Elastic Moduli. A dynamical torsion pendulum
`method was used to determine the modulus of rigidity,
`G, in ten different ternary systems based on the Cu-Zn
`system. Details of the sample preparation and appara(cid:173)
`tus are described elsewhere. u Room temperature data
`were obtained for polycrystalline alloys. The spontane(cid:173)
`ous transformation temperature, which was varied by
`choosing different chemical compositions, was in the
`range between - 18° and - 169°C. Alloy compositions,
`transformation temperatures, and G values are given
`in Table II. It may be seen that the shear moduli of
`the ternary alloys are approximately the same as the
`binary Cu-Zn f3 ' phase alloys, i.e., - 2 x 10 11 dynes
`per sq cm. G does not appear to be related to the
`martensitic transformation temperature, Ms , in con(cid:173)
`trast to some other alloy systems. 12
`
`III) DISCUSSION
`Pseudoelastic strains as large as 15 pct have been
`observed in single crystals and polycrystalline sam(cid:173)
`ples of Cu-Zn-Si and Cu-Zn-Sn beta phase alloys
`during loading in tension, compression, or bending.
`This phenomenon may be described as a stress induced
`pseudoelasticity. For simplicity, the term STRIPE will
`be adopted in the following discussion. STRIPE differs
`from normal elastic behavior in that stress does not
`vary linearly with strain. In addition, the stress-strain
`curve during loading is not the same as the curve dur(cid:173)
`ing unloading. The appearance of a hysteresis loop
`and the small amount of strain remaining in the sam(cid:173)
`ple after unloading suggest that the martensitic trans(cid:173)
`formation is not completely reversible on unloading.
`Interaction between martensite plates and either prior
`f3' phase grain boundaries or o: precipitates, and pos(cid:173)
`sible interactions between plates on different habit
`
`Table II. Shear Moduli of Ternary Cu·Zn Based /3' Phase Alloys
`
`Alloy At. pct.
`No .
`Cu
`
`At. pct.
`Zn
`
`At. pct.
`3rd Element
`
`Ms Temper· G X 10'11 dynes
`ature, °C
`per sq cm
`
`G
`H-1
`H-2
`H-3
`J.J
`l-2
`J•I
`J-2
`K
`L-1
`L-2
`[,.3
`M
`N
`0-1
`0-2
`0-3
`P,1
`P,2
`p.3
`Q
`
`60.5
`60.15
`59.45
`57.7
`60.25
`59.75
`60.25
`59.75
`60.5
`60.65
`61.25
`62.0
`61.25
`61.0
`61.0
`62.0
`63.5
`61.0
`62.0
`63.5
`62.75
`
`39.5
`39.6
`39.8
`40.3
`39.5
`39.5
`39.5
`39.5
`39.25
`39.2
`38.0
`36.5
`38.0
`38.75
`38.75
`37.25
`35.0
`38.5
`37.25
`35.0
`36.5
`
`0.25 Ni
`0.75 Ni
`2.0Ni
`0.25 Ag
`0.75 Ag
`0.25 Au
`0.75 Au
`0.25 Cd
`0.15Ga
`0.75 Ga
`1.5 Ga
`0.75 In
`0.25 Ge
`0.25 Sn
`0.75 Sn
`1.5 Sn
`0.25 Si
`0.75 Si
`1.5 Si
`0.75 Sb
`
`- 126
`-
`)28
`- 136
`- 169
`- 139
`-153
`- 126
`- 132
`- 149
`- 135
`- 99
`- 84
`- 140
`-
`!07
`- 124
`- 99
`- 44
`-142
`-96
`-18
`- 37
`
`2.00
`1.64
`1.84
`2.55
`1.84
`1.81
`1.73
`1.71
`1.4 1
`1.80
`2.88
`1.93
`1.95
`1.60
`J.57
`2.0
`2.0
`1.73
`2.05
`2.91
`2.14
`
`256- VOLUME I, JANUARY 1970
`
`METALLURGICAL TRANSACTIONS
`
`COOK
`Exhibit 1010-0010
`
`

`

`plane (variants) within a single grain may produce lo(cid:173)
`calized plastic deformation. Plastic deformation is
`irreversible, and hence would result in permanent set
`after unloading.
`At temperatures above the Ms (but below the T o
`temperature, i.e., the temperature at which the chem(cid:173)
`ical free energies of the parent and product phases
`are equal), the (3' phase is thermodynamically un(cid:173)
`stable and may transform martensitically when suf(cid:173)
`ficient stress is applied to overcome nonchemical
`free energies. In an early study of the martensitic re(cid:173)
`action in steels, Scheil13 postulated that an (austenitic)
`lattice becomes both mechanically and thermodynam(cid:173)
`ically unstable at the Ms temperature and that a criti(cid:173)
`cal resolved (elastic) shear stress is required to
`promote the martensitic transformation. Mechanical
`instability at the Ms implies that the elastic modulus
`is zero. From the present shear modulus experiments,
`G was approximately 2 x 10 11 dynes per sq cm for all
`of the ternary Cu-Zn based /3' phase alloys, irrespec(cid:173)
`tive of their Ms temperature. If the shear modulus is
`to become zero at the M5 , one would expect some re (cid:173)
`duction in the G value as Ms is approached. Since
`this has not been observed, it is concluded that the /3'
`phase does not become mechanically unstable.
`Internal stresses produced by the change in volume
`accompanying the transformation may be added to the
`external applied stress. The total stress must be less
`than the elastic limit of the {3 1 phase if the resul ting
`martensite phase is to be in equilibrium with the ma(cid:173)
`trix . If this condition is satisfied, it is expected that
`growth of plates would be controlled by the rate of
`change of applied stress. This has been verified by
`metallographic examination of alloys during bending,
`see Fig. 9; the martensite phase grew slowly in the
`lengthwise direction with increasing applied stress and
`disappeared on the removal of the stress. The effect
`of increasing or decreasing the applied load is in this
`case equivalent to cooling or heating the specimen
`through the Ms temperature . Therefore, it should be
`possible to obtain STRIPE in other systems containing
`thermoelastic martensite . In the binary Cu-Zn (3-phase
`alloys, stress induced martensite forms under tensile 14
`or compressive 15 loading, and for small loads disap(cid:173)
`pears when the load is removed. In spite of this me(cid:173)
`chanical reversibility, the total elastic strain achiev(cid:173)
`able under conditions of reversibility is less than -,t
`pct. Adding only a small amount of a third element
`such as silicon or tin increases the reversible elastic
`strains up to -15 pct. A likely explanation for this
`rather remarkable increase is that the third elements
`increase the amount of thermoelastic martensite, 8 and
`expand the range of s t ress in which the elastic mar(cid:173)
`tensite occurs .
`Plastic deformation cannot occur until the sum of
`the applied and the internal stresses exceeds the elas(cid:173)
`tic limit of the {3' matrix. Whereas the stress 1·e(cid:173)
`quired to produce plastic flow generally decreases
`with increasing temperature, the stress required to
`induce the elastic martensitic transformation increases
`with increasing temperature, see Figs. 4 and 7. Con(cid:173)
`sequently, elastic martensite will occur more easily
`at lower temperatures. The variation of the stress to
`form elastic martensite and the plastic flow stress
`with temperature are illustrated schematically in Fig.
`
`13. The curves intersect at a temperature which will
`be called the "critical" temperature, i.e., that tem(cid:173)
`perature where the plastic flow stress is the same as
`the stress required to form elastic martensite. Plas(c